People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Listeria monocytogenes is an organism that can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems, according to the FDA. Healthy individuals may suffer only short-term symptoms such as high fever, severe headache, stiffness, nausea, abdominal pain and diarrhea. Listeria infection can cause miscarriages and stillbirths among pregnant women.

According to Gills Onions website, the recalled lot code is 51RDA1A1A2119 and use-by-dates May 14, 15 and 17,2012. No illnesses have been reported as of yet and no other Gills Onions product is affected by this recall.